The present invention relates to a key switch operable by a cylinder lock comprising a cylinder housing and a cylinder core arranged to be rotatable within the housing, which is coupled with a non-conducting switch rotor, as well as a switch casing base, in which the switching arrangement is located and the switch rotor is guided.
Key switches of this kind are increasingly fitted to electronic equipment in order to prevent unauthorized access or to maintain control. Owing to the high electrostatic potential of a person relative to earth, the insertion of the key can result in a flash-over from the cylinder lock to the fixed contacts of the switching arrangement. The result is then usually malfunctioning of the electronic equipment, since the fixed contacts, in particular those connected to integrated circuits, cannot cope with the resultant loads. For this reason, even the cylinder housing has been provided with an insulating plastic casing and the switching side has been put into a switch rotor of a cup-shaped design which is open-ended towards the key side, which is itself similarly enveloped by a cup-shaped casing cap which is also of insulating material. This particular solution however results in increased size of the switch. This is, however, the only practical means by which the insulation effect can be attained.